\n| 2219<\/td>\n | Welded structures, cryogenic tanks<\/td>\n | Good weldability among high-strength alloys<\/td>\n | Specialized supply<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Alloy and temper names follow the international designation system maintained by the Aluminum Association. The temper suffix matters as much as the alloy number. 7075-T6 and 7075-T7351 are the same alloy, but they behave differently in service.<\/p>\n How to choose between them<\/h3>\nIf the part is primary structure under high static load,\u00a07075 or 7050 is usually specified. 7050 is often preferred for thick plate because its properties hold up better through the section.<\/p>\n If fatigue is the main concern,\u00a02024 is the traditional choice, protected by anodizing, conversion coating or cladding.<\/p>\n If corrosion resistance, weldability or cost matters more than peak strength,\u00a06061 is the practical option for housings, enclosures and non-critical parts.<\/p>\n If the part sees sustained tensile stress in a corrosive environment,\u00a0an overaged temper such as T73 or T7351 is often chosen over T6 to reduce stress-corrosion cracking risk.<\/p>\n These are general patterns. On a real aerospace program, the alloy, temper and material specification are set by the design authority and written on the drawing. A machine shop should never substitute one for another, even if it seems equivalent.<\/p>\n What Tolerances Do Aerospace Aluminum Parts Need?<\/h2>\nAerospace parts aren’t automatically tighter than other industries’ parts. The drawing decides. What sets aerospace apart is how tolerances are specified and proven.<\/p>\n Geometric dimensioning and tolerancing (GD&T)\u00a0is standard on aerospace drawings. Instead of only plus-or-minus dimensions, features are controlled by position, profile, flatness and perpendicularity relative to defined datums. A supplier must be fluent in reading and inspecting GD&T, not just hitting a nominal size.<\/p>\n General tolerances\u00a0cover non-critical features. Critical features, such as bearing bores, fastener hole positions and mating faces, carry tighter individual tolerances.<\/p>\n Every characteristic must be verified.\u00a0On the first article, that means every dimension and note on the drawing, not a sample.<\/p>\n Why holding tolerance on aluminum is harder than it looks<\/h3>\nAluminum is easy to cut but less easy to hold. Three things work against you:<\/p>\n \n- Thermal expansion.\u00a0Aluminum expands by about 23 \u00b5m per meter for every degree Celsius. A 100 mm feature measured 5 \u00b0C warmer than the reference temperature reads about 11 \u00b5m larger. On a \u00b10.01 mm tolerance, that’s most of the band. Serious aerospace shops machine and measure in temperature-controlled conditions.<\/li>\n
- Residual stress.\u00a0Plate and forgings carry internal stresses from manufacturing. When a large percentage of material is removed, as in a heavily pocketed rib, the part can distort. Stress-relieved tempers such as T651 and T7451 help. Roughing, resting and finish machining helps more.<\/li>\n
- Thin walls.\u00a0Lightweight aerospace parts often have thin webs and walls that deflect under cutting forces and clamping. Toolpath strategy, sequencing and fixture design matter as much as the machine. Our guide on \u0627\u0644\u062a\u0635\u0646\u064a\u0639 \u0627\u0644\u0622\u0644\u064a \u0628\u0627\u0633\u062a\u062e\u062f\u0627\u0645 \u0627\u0644\u062d\u0627\u0633\u0628 \u0627\u0644\u0622\u0644\u064a \u0628\u0627\u0633\u062a\u062e\u062f\u0627\u0645 \u0627\u0644\u062d\u0627\u0633\u0628 \u0627\u0644\u0622\u0644\u064a \u0627\u0644\u0631\u0642\u064a\u0642 \u0627\u0644\u062c\u062f\u0631\u0627\u0646<\/a> \u00a0covers the basics.<\/li>\n<\/ol>\n
Which Certifications Do Aerospace Machining Suppliers Need?<\/h2>\n\n\n\n| Requirement<\/td>\n | What it is<\/td>\n | When buyers ask for it<\/td>\n<\/tr>\n | \n| AS9100<\/td>\n | Quality management system standard for aviation, space and defense, built on ISO 9001<\/td>\n | Almost always for production aerospace parts<\/td>\n<\/tr>\n | \n| AS9102 first article inspection<\/td>\n | Standard format for documenting that the first part meets every drawing requirement<\/td>\n | New part numbers, design changes, process changes<\/td>\n<\/tr>\n | \n| Nadcap<\/td>\n | Industry accreditation for special processes such as anodizing, heat treatment and NDT<\/td>\n | When the supplier performs those processes on your parts<\/td>\n<\/tr>\n | \n| ITAR registration<\/td>\n | US export control registration for defense articles and technical data<\/td>\n | US defense programs and controlled drawings<\/td>\n<\/tr>\n | \n| Material traceability<\/td>\n | Mill certificates linked to each batch through to the finished part<\/td>\n | Always<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n AS9100\u00a0is published by the International Aerospace Quality Group as the 9100 quality management standard. It adds aerospace-specific requirements to ISO 9001, including configuration management, risk management, product safety, counterfeit parts prevention and first article inspection. Most primes and tier-one suppliers require it of their machining suppliers.<\/p>\n ITAR\u00a0applies if your drawing contains controlled technical data for a US defense article. The rules are set by the US State Department, and the DDTC’s ITAR overview is the place to start. ITAR-controlled work generally can’t be sent to foreign suppliers without authorization. Check this before you send a single drawing, not after.<\/p>\n A practical warning: ask for the certificate itself and check that it covers the site that machines your parts and the scope you need. A certificate held by a parent company, a sales office or a platform doesn’t automatically cover every factory in its network.<\/p>\n What Documentation Comes With Aerospace Machined Parts?<\/h2>\nThe documentation package is part of the product. A typical aerospace aluminum order ships with:<\/p>\n \n- Material certificate\u00a0from the mill, showing alloy, temper, specification, heat or lot number, chemistry and mechanical properties<\/li>\n
- Certificate of conformance\u00a0signed by the supplier<\/li>\n
- First article inspection report\u00a0in AS9102 format for new parts or changes<\/li>\n
- Dimensional inspection report,\u00a0often from a CMM, for critical characteristics on each lot<\/li>\n
- Special process certificates\u00a0for anodizing, conversion coating, heat treatment or NDT, from approved processors<\/li>\n
- Traceability records\u00a0linking each part or lot back to its material heat<\/li>\n<\/ul>\n
The most common rejection we hear about isn’t a dimension. It’s a missing or mismatched document: a mill cert for the wrong heat number, a finish cert that doesn’t reference the specification on the drawing, or an FAI that skipped the notes. Ask your supplier for a sample documentation package before you place the first order.<\/p>\n Surface Treatments for Aerospace Aluminum<\/h2>\nBare aluminum parts rarely fly. Aerospace drawings usually call for one or more of these:<\/p>\n \n- Chromic or sulfuric acid anodizing\u00a0for corrosion protection and paint adhesion. Sulfuric anodize (Type II) is common; chromic anodize (Type I) appears on older or fatigue-sensitive designs.<\/li>\n
- Hard anodizing (Type III)\u00a0for wear surfaces, with dimensional growth that must be allowed for in machining.<\/li>\n
- Chemical conversion coating\u00a0for conductive, corrosion-resistant surfaces, often used under primer or where electrical bonding is needed.<\/li>\n
- Primer and paint\u00a0to the program’s specification.<\/li>\n<\/ul>\n
Each step changes surface condition or dimensions, so finish requirements should be read before machining, not after. Bores that must stay bare need masking, and hard anodize growth must be built into the machined size.<\/p>\n DFM Tips for Machined Aerospace Aluminum Parts<\/h2>\nWeight-saving pushes aerospace designs toward thin webs and deep pockets. A few design choices make those parts cheaper and more reliable to machine:<\/p>\n \n- Use generous internal corner radii\u00a0in pockets. Larger radii allow larger, stiffer cutters and reduce chatter on thin walls.<\/li>\n
- Keep floor-to-wall transitions consistent\u00a0so the same tool can finish multiple pockets.<\/li>\n
- Balance material removal\u00a0on both sides of a plate to limit distortion.<\/li>\n
- Specify stress-relieved tempers\u00a0such as T651 or T7451 for heavily machined plate.<\/li>\n
- Put datums on stable, accessible features\u00a0that won’t move as material is removed.<\/li>\n
- Limit the number of setups.\u00a0Five-axis machining reduces re-clamping errors on complex fittings.<\/li>\n
- Agree on edge breaks and deburring standards\u00a0early. Sharp edges are a common reason for rework on aerospace parts.<\/li>\n<\/ol>\n
Common Machined Aluminum Aerospace Parts<\/h2>\nThe same alloys show up across very different parts. How each is machined depends on its shape and job.<\/p>\n Brackets and fittings.\u00a0Usually 7075 or 2024, machined from plate or bar. Fittings carry concentrated loads through bolt holes, so hole position, edge distance and surface finish around the holes get close attention. Five-axis machining is common when holes sit on angled faces.<\/p>\n Ribs, frames and bulkheads.\u00a0Large, heavily pocketed parts, often from 7050 or 7075 thick plate. Most of the plate is machined away. Distortion control, through rough-rest-finish sequencing and balanced material removal, is the main challenge.<\/p>\n Avionics housings and electronic enclosures.\u00a0Commonly 6061, with thin walls, connector cutouts and sealing faces. Chemical conversion coating is common where electrical bonding is required.<\/p>\n Hydraulic and fluid manifolds.\u00a0Blocks with intersecting drilled passages, threaded ports and sealing surfaces. Cleanliness, burr removal inside passages and pressure testing matter as much as dimensions.<\/p>\n UAV arms, motor mounts and payload brackets.\u00a0Often 6061 or 7075, optimized for weight. Volumes are higher than in traditional aerospace, so cost per part gets more attention.<\/p>\n Tooling, fixtures and ground support equipment.\u00a06061 and MIC-6 plate, machined to industrial tolerances. These parts support production rather than fly, so documentation requirements are usually lighter.<\/p>\n Lead Times for Aerospace Aluminum Parts<\/h2>\nAerospace lead times are usually set by everything around machining, not the cutting itself.<\/p>\n Material.\u00a0Common grades such as 6061-T651 and 7075-T651 plate are widely stocked. Thick 7050-T7451 plate, specific specifications or certified material with full traceability can take longer to source. Ask about material availability at the quote stage.<\/p>\n Special processes.\u00a0Anodizing, conversion coating and heat treatment through approved processors often run on their own schedules. Allow time for queues and certificates.<\/p>\n First article inspection.\u00a0A full AS9102 FAI on a complex part with many characteristics takes real inspection time. It’s a one-time cost per part number, but it needs to be in the plan.<\/p>\n Customer approval.\u00a0Some customers review the FAI package before releasing production. That review time belongs in the schedule too.<\/p>\n The practical lesson: give your supplier the full requirements, including material spec, finish spec and documentation needs, in the RFQ. A quote based on the drawing alone will understate the lead time.<\/p>\n What Commonly Goes Wrong on Aerospace Aluminum Orders<\/h2>\nFrom what we see across aerospace and defense RFQs, the problems are rarely about machining capability. They’re about information.<\/p>\n \n- Material spec missing or incomplete.\u00a0“7075” with no temper or material specification can’t be bought correctly.<\/li>\n
- Finish notes that conflict with tolerances.\u00a0A \u00b10.01 mm bore with Type III hard anodize and no masking note can’t be met as drawn.<\/li>\n
- Unclear FAI requirement.\u00a0If AS9102 FAI is required, put it on the purchase order. Asking for it after delivery means re-inspecting parts.<\/li>\n
- Export control discovered late.\u00a0If a drawing turns out to be ITAR-controlled after it has gone to several suppliers, you have a compliance problem.<\/li>\n
- Drawing revision mismatch.\u00a0The supplier quotes revision B while engineering releases revision C. Always confirm the revision on the purchase order.<\/li>\n
- Assuming a certificate covers everything.\u00a0An AS9100 certificate with a scope of “distribution” doesn’t cover machining.<\/li>\n<\/ul>\n
Each of these is cheap to fix before ordering and expensive to fix after.<\/p>\n Prototype vs Production: How Aerospace Requirements Change<\/h2>\nNot every aerospace part needs the full production paperwork on day one.<\/p>\n Concept prototypes and test fixtures\u00a0are often machined to the drawing with a basic inspection report and material cert. They prove fit and function, not flight-worthiness.<\/p>\n Qualification hardware\u00a0goes through the full process: correct material spec, approved special processes, AS9102 FAI and complete traceability. The way it’s made is frozen.<\/p>\n Production parts\u00a0must be made the same way as qualified hardware. Any change to material source, process, machine or location may trigger a new FAI.<\/p>\n That last point matters when choosing a supplier. Switching shops after qualification isn’t a price negotiation. It’s a requalification. So choose the production supplier early, and use them for qualification builds too.<\/p>\n UAV, Space and Ground Support Parts<\/h2>\nThe aerospace label covers a wide range. Requirements differ:<\/p>\n | |